1. Field of the Invention
The present invention is generally directed toward apparatus and method for introducing seed into an existing stand of vegetation in a manner that will replace or improve the quality of the existing vegetation. More specifically, the present invention maximizes the germination and growth of newly introduced seed without removal of the existing plant variety.
2. Description of the Prior Art
In certain circumstances, it may be advantageous to convert an existing area of vegetation to new vegetation. For example, the turf used on golf courses, athletic fields, lawns or parks may be replaced to take advantage of new plant varieties more suited to a particular climate, use or care requirements.
Different climate zones exist throughout the world. Plant species that grow and thrive in one climate zone may not survive if planted in a climate zone to which they have not adapted. For example, grasses commonly used on cool-season lawns, such as Kentucky bluegrass, do not tolerate the hot summers of the southern U.S. and are not grown there. Likewise, warm-season grasses, such as bermudagrass, cannot be grown in the northern U.S. The area between what is commonly understood to be a cool climate zone (north of about 40° latitude in the U.S.) and a warm climate zone (south of about 34° latitude in the U.S.) is generally referred to as a climate transition zone. The climate in this area is characterized by extreme periods of hot and cold temperatures as well as periods of frequent precipitation and lack of precipitation.
Because the climate in the transition zone is characterized by these temperature and moisture variations, it can be difficult to maintain plant species that can survive the temperature and moisture extremes. It is common for golf course superintendents and other turfgrass managers in the transition zone to grow cool-season grasses that can survive the cold winter months. However, these grasses often require large water and pesticide inputs to survive during summer months.
Several new varieties of seeded warm-season grasses have recently become available that provide good turf quality during hot summer temperatures and require significantly less water and pesticide inputs than cool-season grasses. These new warm-season grasses can also survive the cold winter months. Transitioning from the use of cool-season grasses to the newer varieties of warm-season grasses can have a positive environmental impact by reducing water and fertilizer use. In addition, the resulting reduction in fertilizer and water use also provides economic benefit.
Turfgrass managers wanting to convert cool-season turfs to seeded warm-season turfs currently have several options. Warm-season grasses can be seeded directly into the existing stand of cool-season grasses with no seedbed preparation. This approach results in little seed germination and may require many years for complete conversion. Another option is to kill existing vegetation by application of a non-selective herbicide and then overseeding the area. However, this method requires the application of a large amount of seed. Further, the applied seed generally lies upon the soil surface and can lead to inefficient seed germination and a long conversion process. Yet another option is to replace strips (approximately 4-inches wide) of existing turf with new sod. This is a relatively expensive and time consuming method. Still another option is to insert sprigs of grass into the existing turf and allowing the sprigs to grow laterally and eventually out compete the existing vegetation. While effective, this method is still relatively expensive. Lastly, the entire area can be sodded with new vegetation, however, this is the most expensive alternative.
Currently, conversion by seeding is usually accomplished by the complete removal of the existing turf, either by rototilling or through the use of a non-selective herbicide to kill the existing cool-season turf. Warm-season seed is then broadcast over the prepared surface. The removal of the existing turf requires that the area being converted be closed for use until the new seed can be established which can often last for several months. For golf courses, this results in course closure and a significant loss of revenue. It would be most desirable if the area could remain open for use or play during the period when cool-turf areas are being converted to seeded warm-season grasses.
As an alternative to replacement, existing vegetation stands oftentimes need to be improved. Alfalfa is a herbaceous perennial legume that is distributed worldwide and accounts for nearly thirty million acres of production in the United States. Alfalfa produces a highly palatable feed that is prized as a primary component of dairy cattle rations. It is also an important feed for horses, beef cattle and sheep because of its high content of protein, vitamins and minerals.
After seeding, alfalfa stands can remain productive for about four to ten years or even longer. As stands become older, the plant populations decrease along with the overall feed value of the product. When this occurs, renovation or rejuvenation of the crop becomes necessary. Although current practice commonly calls for alfalfa to be grown in a crop rotation program with grain crops, many alfalfa producers who raise crops on soils that are marginal for commercial grain productions would prefer a method that allows for continuous alfalfa production. Attempts at inter-seeding or drilling more seed as the crop begins to decline have been unsuccessful due to the effects that crowding, shading, and auto-toxicity have on new seedlings that are planted with traditional seeding equipment. Current conventional disc or hoe opener seeding equipment do little more than place seed in small slits or scarifications along the ground. Such equipment, often referred to as “slit-seeders,” slice very narrow furrows (⅛ inch wide) with variable spacing (0.5-2 inches) into the existing stand of vegetation and drops seed into these depressions. Seedlings from slit-seeders come up within a stand of dense existing vegetation and are unable to compete with the existing plants.
There is a need in the art for a method of converting cool-season turf areas to seeded warm-season grasses in a manner that uses less seed, increases germination rate and survival, and allows the cool-season turf area to remain open for use or play during the conversion period. There is also a need in the art for a method of improving the quality of existing vegetation by thickening marginal stands of existing vegetation.